To understand attrition analysis, one has to understand what is attrition. Attrition, in simple industry terms is the number of people who quit the services of an organization voluntarily. Attrition analysis, therefore, is a method of finding out reasons as to why employees quit, what are the contributing factors to it, what could have been done by the organization to retain them, what can be done to prevent future attrition for similar reasons, etc. To do attrition analysis, there has to be an exit interview or discussions (either formally or informally, but most organizations have a formal process to do it). During exit interview/discussions, every employee who is quitting the organization is asked about the reasons of his leaving, what did go well and what did not, what the organization should have done to retain him/her. When you compile the data of every employee who quit the organization over a period of time, you compile the reasons and see what are the major reasons. Based on that, you can do your analysis and recommend corrective and preventive actions.